Colorimetric Based Polysorbate Crosslinked Cellulose-Ag-Cu Nanohybrid Sensor for Urea Sensing Applications

Non-enzymatic colorimetric based sensors are rapidly emerging sets of sensors. In this study, cellulose-Ag-Cu nanohybrids were designed to sense urea based on the change in absorbance obtained after the nanohybrid and urea contact. The cellulose-Ag-Cu nanohybrids were characterized with FTIR, SEM, XRD and BET. The bands at 1120, 680 and 620 cm(-1) represents the C-O-C of the biopolymer glycosidic linkage, the Ag-O and Cu-O bands while the SEM shows well dispersed nanoparticles with less agglomeration on the cellulosic rods. Braggs diffraction peaks emerged at 2 theta angles of 18, 38, 44, 64.5 and 79 degrees for the cellulose-Ag-Cu nanohybrid corresponding to the crystalline domain of the cellulose and 111, 200, 220, 222 face centred cubic crystal planes of silver and copper respectively while the BET gave the value of 162.465 as the nanohybrid surface area. The curve of colorimetric concentration versus the prepared urea concentration was fitted on Boltzmann model and a general equation was constructed for the sensing. The limit of detection of the nanohybrid corresponds to 0.8102 ppm urea concentration. The change in absorbance of the nanohybrid increases as the urea concentration increases but decreases as pH increases. The effect of salts was also evaluated and the change in absorbance increases due to indirect oxidation.